Polymeric resins have long been known for their chemical and physical properties. Molded or extruded resins have found numerous applications, such as in appliances, consumer products, electronics, machine components, automotive parts and the like. However, the physical and chemical properties of the polymeric resins, and thus the components or articles fabricated therefrom, vary widely depending upon the chemical structure of the main chain or backbone of the polymeric resins, as well as the molecular weight of such polymeric resins.
For example, polycarbonate resins are known to possess desired heat distortion temperatures, but suffer in that such polymeric resins, and thus articles molded or extruded therefrom, generally possess low chemical resistance to solvents, low stress crack resistance, and low impact strength when thick sections of the polymer are required or utilized. On the other hand, polymeric resins, such as the polyamides (i.e. the nylons), are known to be chemically resistant to a large number of solvents, and to have a desired degree of toughness and abrasion resistance. However, the polyamide polymers also possess certain inherent disadvantages, unless modified, such as relatively low impact strength, a low heat distortion temperature, and ., an affinity to pick up moisture.
In order to modify the properties of polymeric resins, mixtures of selected polymeric resins have been utilized to form blends. However, in many cases, such as with polycarbonate and polyamide resins, such resins are incompatible. Attempts to render such resinous materials compatible have generally involved expensive chemical compatabilizing compounds or process conditions, and even then the resulting resinous blend often does not possess the desired properties.
Compatabilizing compounds of the past have comprised compounds containing carboxylic acid. These carboxylic acid compounds are corrosive to the molding equipment utilized in processing the polymeric material in which these compatablizing agents are used. In addition, compatabilizers containing carboxylic acids do not retain paint adhesive properties when painted polymer blends utilizing these compatabilizers are exposed to high levels of humidity. A non-corrosive compatabilizing agent which does not contain a carboxylic acid would be desireable.
Stabilizing agents are well known in the art and may be utilized to end cap the polyamide component of a polymeric blend. Such stabilization is desireable in that the overall stability of the polymeric blend may thus be maintained. Although stabilizing agents, such as the diglycidyl epoxides have been efficient in terminating polyamide chain propogation, these epoxides cross-link proximate polymers and thus increase the molecular weight of the blends which incorporate them. Increased molecular weight of the blend decreases flow rate at a given processing temperature and requires increased temperature, and thus energy expenditures to achieve a satisfactory flow. A stabilizing agent which does not exhibit cross-linking of the polymer blend, and thus increases processing efficiency is needed.
Polycarbonate and polyamide blends may be utilized in a mold process applications, such as injection molding, whereby finely detailed or acutely angled areas of a mold must be substantially filled with such blends. Such molds necessitate a low viscosity blend whereby increased flow rates are provided so as to allow such areas to be filled. Increasing the processing temperature of the blend is often necessary to acheive a low viscosity so as to provide the required flow. Stabilizers of the past have been unable to retain polycarbonate and polyamide blend toughness, or impact strength after said blend had been exposed to the increased processing temperatures required in these finely detailed molding applications. It would be desireable to discover a stabilizing agent for such blends which would allow increased temperature processing of said blend without the loss of blend impact strength.
Polyamide polycarbonate blends of the past have benefited from impact strength provided by the polyamide. However, these blends have exhibited rather poor low temperature impact resistance. Impact modifying agents have been utilized in the past to increase the toughness of the blend, but these agents have not optimized low temperature impact strength. An impact agent which imparts increased low temperature impact strength to polyamide polycarbonate blends is needed.